We had a horrible cold spell earlier this winter, with nearly unheard of lows. However, as I walked to work each morning, and visited our community garden, the biggest killer during that time was not frost nor freeze. It was drought.
Lack of water combined with extreme temperatures is a sure way to kill even hardy perennials! Whether dormant or not, plants need some water to survive the winter. Plants spend the winter protecting themselves from the cold, and getting ready for spring. (Even bulbs and root crops do this.) They are still alive!
When You Need To Water
There are several methods for measuring how much water your plants have received.
- Calendar Method. Keep a calendar of when it rains. If it hasn’t rained or snowed in 3 weeks, or in 1 week that includes high winds, water! Did I say snow? I did. The rule of thumb is that one foot of snow has 1 inch of moisture. 1 inch in the winter will usually last about 3 weeks, or 1 week if the air is really dry from wind.
- Water Gauge Method. Measure the moisture. You can buy a cheap water gauge in your local hardware store. Stick it in the soil, and it will tell you how wet the soil is. It should read moist but not wet. If it reads dry, water.
- Soil Grab Method. If you hate calendars, and you hate gauges, dig down 8 inches or so. Then grab a handful of soil, and press it together in your palm. If it sticks together, it’s fine. If water drips out, it’s definitely wet. But if it doesn’t stick together, it’s too dry and you need to water.
If you live in an area where the ground freezes solid for months at a time (so frozen that it never thaws during the day), you may not need to water. But be ready as soon as the soil begins to unfreeze during the day. Frozen soil will still absorb water and dissolve the ice, which can help aerate the soil and make sure your plants are receiving enough water. You’ll have to judge how frozen your soil really is.
If you have potted plants, be particularly watchful as they are more prone to freezing and more prone to drought. They will dry out faster than plants in the ground, so if you use the calendar method, they should be watered once a week between rains.
What Time of Day to Water
Water in the late morning to early afternoon, preferably when the soil is nearing its warmest point of the day, so the soil has time to warm before the cool or freezing night temperatures. It also helps to mix a bit of hot water with the tap water, so that the water is tepid rather than ice cold.
How To Water
A general rule for winter is to water when the soil is dry, and only water until the soil is moist, not wet.
Do not water leaves, stem, or trunk! Water the soil not the plant. In other words, water where the roots are: find the distance halfway between the stem or trunk and the outer reach of its branches. Start watering from that point, and water in a circle all the way to the outer stretch of the branches.
Water when soil is dry and only water until soil is moist, not wet. If you have drip irrigation, this is a good method. Otherwise, a hose is fine.
Special Circumstances: Dangers of Frost
There are a few other times when you might want to water. If it is nearing your first frost, and you are trying to protect your tomatoes or other crops through the last few days before a hard frost kills them, water toward the end of the day. The reason is this: water evaporates at night, and as it evaporates it will slightly warm the air. This might be just enough to keep your plants from frost late in the season.
The same circumstance might occur early in the season, when you’ve transplanted your seedlings thinking your last frost has come and gone. But whoa, at the last minute you hear a frost warning coming your way. Go water (unless the soil is already wet). Avoid the stems, but go water. Just a bit, to make the soil moist. I find that watering with water that is slightly warm (just above tepid) helps quite a bit.
A dear reader wrote me recently to remind me to take care of my house plants. She’d seen a photo of my apartment, and was saddened to see a bit of plant neglect (it’s true – when I get busy, I do forget them). So same goes for your houseplants: particularly in winter, when the insides are dry due to the heat being on, don’t forget to water your plants!
Any Other Tips, Tenured Gardeners?
Please add to this!